It has been reported that the levels of violence differed according to the neighborhoods, but often groups of unsupervised teens had higher levels of violence, including many relatively "good" neighborhoods where residents say they trust and help each other and watch each other's children.

Browning and David Maimon, a former Ohio State graduate student, measured levels of what sociologists call "collective efficacy" in each neighborhood, neighbors trust each other, are willing to help each other and intervene to control public spaces and help keep each other's kids in line.

Published in the journal Criminology, the study finds neighborhoods with high levels of collective efficacy tended to have lower levels of violence, but parents in these high-collective-efficacy neighborhoods were also more likely to let their teens out unsupervised.

Browning says in a statement, "Even if you trust all your neighbors and all the teens are 'A' students, it is best to assume that groups of teens just hanging out can lead to problems, including violence." (With Inputs from Agencies)